Van Hove singularity in the magnon spectrum of the antiferromagnetic quantum honeycomb lattice.

ABSTRACT: In quantum magnets, magnetic moments fluctuate heavily and are strongly entangled with each other, a fundamental distinction from classical magnetism. Here, with inelastic neutron scattering measurements, we probe the spin correlations of the honeycomb lattice quantum magnet YbCl₃. A linear spin wave theory with a single Heisenberg interaction on the honeycomb lattice, including both transverse and longitudinal channels of the neutron response, reproduces all of the key features in the spectrum. In particular, we identify a Van Hove singularity, a clearly observable sharp feature within a continuum response. The demonstration of such a Van Hove singularity in a two-magnon continuum is important as a confirmation of broadly held notions of continua in quantum magnetism and additionally because analogous features in two-spinon continua could be used to distinguish quantum spin liquids from merely disordered systems. These results establish YbCl₃ as a benchmark material for quantum magnetism on the honeycomb lattice.

SUBMITTER: Sala G 

PROVIDER: S-EPMC7794317 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature